Black Light and the Criminal

Ultra-violet rays, now readily accessible to law enforcing bodies, adds another weapon to the arsenal of the government's war on lawlessness.
THE use of filtered ultra-violet light for crime detection and identification purposes has been made available by the presentation of a comparatively low cost, yet powerful, efficient and portable black-ray quartz lamp. Specially formulated dark-colored Wood's glass filters in the front of lamp hold back the visible light emitted by the mercury arc and allow only a concentrated beam of invisible ultra-violet, or "black light," to pass. This ray cannot be seen by the eye, even in the dark or semi-dark, yet its radiations are absorbed by a wide variety of substances and instantly re-emitted as visible light of constant intensity and color.